"He opened the door for her and watched her walk away down the huge corridor, then hesitate at the top of the stairs. Heads turned as she passed. You sensed she came from a different world, the world of the night, and there was something almost indecent about her in the harsh light of a winter's day." A young cabaret dancer in a black silk dress leads Inspector Maigret into a seamy world of nightclubs, drug addiction and exploitation on the streets of Montmartre.